Embolus blood clot filter delivery system

ABSTRACT

A blood filter delivery system for delivering a blood filter into a vein includes a push rod for pushing the blood filter through and out of a catheter, the push rod having a filter positioning assembly on one end. The filter positioning assembly includes positioner members, which retain anchor members of the filter. The filter positioning assembly can position the end of the delivery catheter near the blood vessel centerline before releasing the filter&#39;s anchor members, thereby helping to align the blood filter along the centerline of the blood vessel.

PRIORITY DATA AND INCORPORATION BY REFERENCE

This application is a continuation of U.S. patent application Ser. No.15/219,015, filed Jul. 25, 2016, which was a continuation of U.S. patentapplication Ser. No. 14/248,859, filed Apr. 9, 2014, which was acontinuation of U.S. patent application Ser. No. 12/096,783, filed Aug.20, 2009, which was a U.S. National Stage application under 35 U.S.C.371 of International Application No. PCT/US2006/062725, filed Dec. 29,2006, which claims benefit of priority to U.S. Provisional PatentApplication No. 60/754,636, filed Dec. 30, 2005 which is incorporated byreference in its entirety. This invention is related to the subjectmatter shown and described in the following: (i) PCT InternationalApplication No. PCT/US06/62722, filed Dec. 29, 2006, entitled “RemovableBlood Clot Filter with Edge For Cutting Through the Endothelium” andclaiming the benefit of priority to U.S. Provisional Patent ApplicationNo. 60/754,600, filed Dec. 30, 2005; (ii) PCT International ApplicationNo. PCT/US06/62719, filed Dec. 29, 2006, entitled “Embolus Blood ClotFilter with Post Delivery Actuation,” and claiming the benefit ofpriority to U.S. Provisional Patent Application No. 60/754,633, filedDec. 30, 2005; (iii) PCT International Application No. PCT/US06/62733,filed Dec. 29, 2006, entitled “Embolus Blood Clot Filter Removal Systemand Method,” and claiming the benefit of priority to U.S. ProvisionalPatent Application No. 60/754,598, filed Dec. 30, 2005; (iv) PCTInternational Application No. PCT/US06/62720, filed Dec. 29, 2006,entitled “Embolus Blood Clot Filter with Floating Filter Basket,” andclaiming the benefit of priority to U.S. Provisional Patent ApplicationNo. 60/754,599, filed Dec. 30, 2005; and (v) PCT InternationalApplication No. PCT/US06/62730, filed Dec. 29, 2006, entitled “EmbolusBlood Clot Filter with Bio-Resorbable Coated Filter Members,” andclaiming the benefit of priority to U.S. Provisional Patent ApplicationNo. 60/754,597, entitled “Embolus Blood Clot Filter with Retainers onLocator Filter Members,” filed Dec. 30, 2005, each of which is herebyincorporated by reference in its entirety.

TECHNICAL FIELD

This invention relates to a device for delivering a blood filter into avessel of a patient's body to reduce the risk of embolisms.

BACKGROUND ART

In recent years, a number of medical devices have been designed whichare adapted for compression into a small size to facilitate introductioninto a vascular passageway and which are subsequently expandable intocontact with the walls of the passageway. These devices include, amongothers, blood clot filters, which expand and are held in position byengagement with the inner wall of a vein, such as the vena cava. Thesevena cava filters are generally designed to remain in place permanently.Typically, blood filters are made of metal wire in a configurationdesigned to fill the cross section of the blood vessel with filtermembers. Such filters must be radially compressed to fit within adelivery catheter, and these filters include structure to anchor thefilter in place within the vena cava, such as elongate diverging anchormembers with hooked ends that penetrate the vessel wall and positivelyprevent longitudinal migration of the filter in either direction withinthe vessel.

Known systems and methods for delivering a blood filter to a location ina patient's blood vessel are disclosed, such as in U.S. Pat. No.6,258,026, which is hereby incorporated by reference in its entirety.Typically, a filter delivery catheter is positioned within a patient'sblood vessel by threading it through a major vein or artery from a pointof access, such as the jugular or femoral veins. Once the distal end ofthe catheter is in position where the filter is to be delivered, theblood filter is placed in the proximal end of the catheter and pushedthrough to the distal end by a pusher member, such as a stiff wire. Whenthe filter is pushed out of the distal end of the catheter, the filtermembers spring radially outward to contact the blood vessel's wall. Thehooked ends of the anchor members engage the vessel wall and hold thefilter in place.

Known systems and methods for installing blood filters have deficienciesand drawbacks. One such deficiency with known delivery devices makes itdifficult to align the filter for implantation because there is no selfacting mechanism for centering the delivery catheter.

DISCLOSURE OF INVENTION

The various embodiments provide for blood filter delivery systems thatalleviate the deficiencies of known delivery systems and filters. In anembodiment, an apparatus for pushing a blood filter from a deliverycatheter includes a plurality of positioner or positioning memberscoupled to the distal end of a push rod assembly. The positioner membersare configured so that they will fit over the hooked ends of the filteranchor members, gripping the anchor members when the filter andpositioner members are situated in a catheter or storage tube. Thepositioner members are shaped and coupled to a hub on the push rodassembly so that when they extend beyond the end of the catheter, thepositioner members bend away from the centerline of the catheter andpush rod assembly. The positioner members are sized and shaped so thattheir distal ends will contact and push against the blood vessel wallbefore the filter or the entire positioner member is beyond the end ofthe catheter. By pressing on the blood vessel wall, the positionermembers bring the end of the catheter into near alignment with thecenterline of the blood vessel. The positioning action happens beforethe filter's anchor members are released by the positioner members.

In an embodiment, a filter deliver system includes a catheter and afilter positioning assembly situated within the catheter. The filterpositioning assembly includes a hub and a plurality of positionermembers coupled to the hub. Each of the plurality of positioner membersincludes an end that cooperates with and retains the plurality of anchormembers within the catheter when the ends of the positioner members aredisposed within the catheter.

In another embodiment, a filter delivery assembly for delivering a bloodfilter having a plurality of anchor members into a blood vessel includesa storage tube within which are positioned a blood filter and a filterpositioning assembly. The filter positioning assembly includes aplurality of positioner members forming a retaining boundary thatcontains the plurality of filter anchor members. An elongated push rodmay be coupled to the filter positioning assembly.

Another embodiment is a push rod assembly for use in delivering into ablood vessel via a catheter a blood filter having a plurality of anchormembers. The push rod assembly includes a push rod extending along alongitudinal axis from a first end to a second end, a handle disposedproximate the first end, and a filter positioning assembly disposedproximate the second end. The filter positioning assembly has alongitudinal axis and includes a hub and a plurality of positionermembers coupled to the hub. Each of the plurality of positioner membersis curved and oriented so that the positioner members extend away fromthe longitudinal axis when unconstrained, and are configured to collapsetoward the longitudinal axis so as to retain the plurality of anchormembers when the positioner members and blood filter are situated withinthe catheter.

In another embodiment, a filter delivery system includes at least acatheter introducer, a filter storage tube, a push rod assembly having afilter positioning assembly on its distal end, with the filterpositioning assembly including a plurality of anchor retention members.The catheter introducer has a coupling port connected to an elongatedgenerally tubular member. The storage tube is configured to be coupledto the coupling port of the introducer and an adaptor, such as aTouhy-Borst Adapter. The push rod assembly has a first end that may bedisposed in the storage tube and a second end extending out of theTouhy-Borst Adapter. The push rod assembly may include a handle, a pushwire, and a filter positioning assembly engaged to a blood filter. Thehandle may be disposed along a longitudinal axis of the push rodassembly proximate the second end. The push rod is disposed along thelongitudinal axis proximate the first end of the push rod assembly. Thefilter positioning assembly is disposed on the distal end of the pushrod assembly along the longitudinal axis. In an assembled, pre-deliveryconfiguration, a blood filter, which has a plurality of anchor membersdisposed about the longitudinal axis each having a hook on the end, isfolded into a narrow profile and captured by the filter positioningassembly by folding the positioner members over the anchor members ofthe filter. The assembled filter and filter positioning assembly aresituated within the filter storage tube.

In another embodiment, a method of packaging a blood filter having aplurality of anchor members coupled to a hub and disposed about alongitudinal axis is disclosed. The method includes folding theplurality of anchors generally parallel to the longitudinal axis,enclosing the plurality of anchors within a plurality of positionermembers coupled to a push rod assembly, and enclosing the filter and thepositioner members in a generally tubular member.

In another embodiment, a method of delivering a blood filter into ablood vessel via a catheter (an end of which is situated within a bloodvessel) is disclosed. The method preferably includes pressing against awall of the blood vessel with a plurality of positioner members,retaining anchor members of the blood filter until the plurality ofpositioner members exit the catheter, and preventing the anchor membersof the blood filter from engaging the blood vessel wall until thecatheter is positioned in near alignment with the centerline of theblood vessel.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and constitutepart of this specification, illustrate presently preferred embodimentsof the invention, and, together with the general description given aboveand the detailed description given below, explain features of theinvention.

FIG. 1 is a perspective view of an embodiment of a blood filter.

FIG. 2 is a side perspective view of the filter of FIG. 1 in a foldedconfiguration.

FIG. 3 is a perspective view of the blood filter of FIG. 1 positionedwithin a blood vessel.

FIG. 4 is a perspective view of the blood filter of FIG. 1 positioned atan angle within a blood vessel.

FIG. 5 is a perspective view of the blood filter of FIG. 1 at a stage ofdelivery to the blood vessel.

FIG. 6 is a side view of a push rod assembly for delivering a filter ofthe type illustrated in FIG. 1 into a blood vessel.

FIG. 7A is a detail view of the filter positioning assembly of the pushrod assembly of FIG. 6.

FIG. 7B is an exploded detail view of the filter positioning assemblyillustrated in FIG. 7A.

FIGS. 7C and 7D illustrate an alternative embodiment of the filterpositioning assembly of FIGS. 7A and 7B.

FIGS. 8A-8C and 9A-9E illustrate various embodiments of the filterpositioning assembly of the push rod assembly illustrated in FIG. 6.

FIG. 10 is a detail view of another embodiment of a filter positioningassembly for use with a push rod assembly such as that shown in FIG. 6.

FIG. 11 is a side view of a filter and the filter positioning assemblyof the push rod assembly of FIG. 6.

FIG. 12 is a sectional view of a filter storage tube including a filterand filter positioning assembly.

FIG. 13A is a side view of an embodiment of the filter positioningassembly including a spline near its base to contain the filter anchormembers.

FIG. 13B is a cross sectional view of the filter positioning assemblyshown in FIG. 13A.

FIGS. 14A-14C are detail views of alternative embodiments of the filterpositioning assembly and a portion of the push rod assembly of FIG. 6.

FIGS. 15-20 illustrate steps in the delivery of a blood filter into ablood vessel.

FIG. 21 is an assembly view of an example embodiment of a filterdelivery system suitable for use with various embodiments of the presentinvention.

FIG. 22 is a side sectional view of a delivery catheter suitable for usewith various embodiments of the present invention.

FIG. 23 is a detail sectional view of portions of the delivery catheterof FIG. 22.

FIG. 24 is a perspective view of portions of the delivery catheter ofFIG. 22.

FIG. 25 is a side sectional view of a catheter expander suitable for usewith various embodiments of the present invention.

FIGS. 26-28 are detail views of portions of the catheter expander ofFIG. 25.

FIG. 29 is a detail view of an adapter portion of the filter deliverysystem of FIG. 21.

FIG. 30 is a perspective view of a filter storage tube portion of thefilter delivery system of FIG. 21.

MODE(S) FOR CARRYING OUT THE INVENTION

The various embodiments will be described in detail with reference tothe accompanying drawings. Wherever possible, the same reference numberswill be used throughout the drawings to refer to the same or like parts.

As used herein, the terms “about” or “approximately” for any numericalvalues or ranges indicate a suitable dimensional tolerance that allowsthe part or collection of components to function for its intendedpurpose as described herein. Also, as used herein, the terms “patient”,“host” and “subject” refer to any human or animal subject and are notintended to limit the systems or methods to human use, although use ofthe subject invention in a human patient represents a preferredembodiment.

The blood filter delivery apparatus and system in the variousembodiments mechanically integrate components to safely and reliablydeliver and emplace a blood filter within a patient's blood vessel, suchas the vena cava. The apparatus and system preferably connects or isprepackaged with a filter in a filter storage tube and assists inproperly positioning the filter in the vein in a reliable fashion.

The various embodiments are intended to be used with a variety of bloodfilters, examples of which are described here to inform the discussionof the embodiments of the present invention. Referring to FIG. 1, ablood filter typically will include a hub 2 to which are coupled aplurality of filter members 20, 30. The filter members 20, 30 bothposition and anchor the filter 1 in the blood vessel and serve as thefilter mesh elements which screen emboli from blood that passes throughthe filter. Common blood filters include anchor members 30 and locatormembers 20.

Anchor members 30 can include a hook 40 or hooks near their distal ends(i.e., the ends opposite from the proximal ends, which are coupled tothe hub 2). The hooks 40 are designed to penetrate and hook into theendothelial layer of the blood vessel to prevent longitudinal migrationof the filter 1 within the vessel. Hooks 40 may have a smaller crosssectional area than the cross sectional area of the anchor members.Anchor members 30 are formed so they flex radially outward, asillustrated in FIG. 1, so their distal ends apply sufficient pressureagainst the blood vessel wall to drive the hooks 40 into the endothelialtissue. In an example filter, the anchor members have a spread ofapproximately 1.6 inches (about 40 millimeters) in an unconstrainedconfiguration (i.e., not installed in the blood vessel).

Locator members 20 also are formed so that when they are released fromthe delivery catheter they flex radially outward so their distal endspress against the blood vessel walls. Without hooks, the locatormembers' 20 distal ends apply generally equal spring force about thecircumference of the vessel wall which, if all locators act together,moves the filter hub 2 toward the vessel's centerline. This centeringmovement positions the filter for proper expansion of the filter members20, 30 and helps ensure forces are applied equally to the vessel walls.

FIG. 3 illustrates a filter installed so its longitudinal axis A isapproximately aligned with the centerline B of a blood vessel 6.Positioning the filter 1 so it is aligned with the vessel's centerline Bhelps to provide proper filter functioning and reduce the potential forinjury to the blood vessel's wall due to application of excessive forceby any one or a few filter members 20, 30.

Typically, filter locator members 20 are spaced equiangularly about thefilter hub 2 so that even spacing exists between the locators 20 toprovide an effective filter basket. For the same reason, anchor members30 are typically positioned equiangularly about the hub 2. To facilitatefolding the filter into its narrowest possible profile (illustrated inFIG. 2) for insertion in a delivery catheter, locator members 20 may beangularly offset from the anchor members 30 about the filter hub 2. Inthis manner, locator members 20 can fit between anchor members 30 in thefolded, pre-delivery configuration.

To facilitate filter centering, common blood filters feature locatormembers 20 that are shorter than the anchor members 30, so that when thefilter is ejected from the delivery catheter hub-end first, the locatormembers 20 deploy before the anchors, thereby centering the filter 1 ata point of equal force on the locator members 20 (i.e., equidistant fromthe locator member 20 ends) before the anchor members 30 deploy. If thefilter 1 is aligned with the vessel centerline B, the filter hub 2 willbe positioned at or near the centerline, as illustrated in FIG. 3. Thiscentering-before-anchoring capability is important because the hooks 40will tend to lock the filter in place once they penetrate theendothelial layer.

While deploying the locator members 20 before the anchor members 30tends to center the filter hub 2 within the blood vessel at a point ofequal force on all locator members, this action may not always align thefilter with the vessel's centerline. In some circumstances, the filter 1may be misaligned within the blood vessel 6 so that the filter'slongitudinal axis A is at an angle to the vessel's centerline B. If themisalignment is significant enough, such as is illustrated in FIG. 4,the filter 1 may have less filtering volume than a properly alignedfilter.

Filter misalignment may occur when a filter 1 is delivered into a bloodvessel 6 with the catheter 16 positioned against the vessel wall, asillustrated in FIG. 5. Due to a host's vessel anatomy, the end of thecatheter 16 may be off center or even resting on a side of the bloodvessel when the filter 1 is ejected. As shown in FIG. 5, with thecatheter 16 misaligned within the blood vessel 6, the centering forceprovided by the locator members 20 may contribute to misaligning thefilter within the blood vessel. To avoid this condition, a clinician mayuse fluoroscopy to view the relative position of the catheter 16 in theblood vessel 6. But this step involves additional procedure time andradiation exposure to the patient.

When the end of the catheter 16 is aligned with the vessel's centerlineB, the anchor members 30 will tend to spring outward and engage thevessel wall 6 so the entire filter 1 is fixed in an aligned orientationwith respect to the vessel's centerline B. The various embodimentsprovide a capability for centering the catheter's end, withoutadditional clinician efforts, using structure which mechanically centersthe catheter within the vessel prior to releasing the anchor members 30.

Referring to FIG. 6, shown is a preferred elongated push rod assembly 60for advancing a filter 1 through a delivery catheter 16. The push rodassembly 60 may include a handle 61 coupled to the proximal end, anextended portion 62 which may feature a number of elements of differentlengths and cross sections 63-67, and a filter positioning assembly 70coupled to the distal end of the push rod 60. The push rod assembly 60has a longitudinal length preferably in the range from about 12 inches(about 300 mm) to about 40 inches (about 1020 mm), and is preferablyabout 36 inches (about 910 mm).

The various elements of the push rod assembly 60 may be made fromdifferent materials. For example, the handle 61 may be formed of anumber of metallic, polymer or plastic materials, and is preferablyformed from PEBA, which is coupled to a stainless steel hollow section63 having a diameter of about 0.041 inches. The hollow stainless steeltube 63 may be connected to a suitable alloy material wire 64,including, for example, a super-elastic shape memory alloy (e.g.,Nitinol), on which various elements can be disposed, such as a stop orboss portion 65. The shape memory alloy can further be defined aspreferably having an austenite finish (A_(f)) temperature below bodytemperature. The stainless steel hollow section 63 may be coupled to anextended wire 64, which may be made from stainless steel, theCobalt-Chromium-Nickel alloy known as Elgiloy®, or a super-elastic shapememory alloy, such as Nitinol. A terminal portion 67, positioned at thedistal end of the extended portion 62, may have a smaller diameter thanthe wire 64, 66 and can be made from stainless steel or Elgiloy®, andmore preferably is made of Nitinol. In a preferred embodiment, theterminal portion 67 has a diameter of about 0.020 inches.

Coupled to the terminal portion 67 is a filter positioning assembly 70which is configured to push the filter 1 through a delivery catheter 16,position the end of the catheter near the center of the blood vesselafter the filter's locator members 20 deploy and delay release of theanchor members 30 until after the catheter end is centered. Referring toFIG. 7A, the filter positioning assembly 70 includes a hub 71 coupled onone end to the terminal portion 67 of the push rod 60. On the other end,the hub 71 is coupled to a number of positioner members 72 whichfunction to: (1) position the end of the catheter at or near thecenterline of the blood vessel; and/or (2) retain filter anchor membersin a collapsed configuration until the catheter end has been centered.

Within the storage tube 15 and delivery catheter 16, the positionermembers 72 fold down over the filter anchor members 30 when the filteris in the folded configuration illustrated in FIG. 2 to present a narrowprofile assembly as illustrated in FIG. 11. For some embodiments, thoughnot all, there is one positioner member 72 for each anchor member 30 inthe filter 1, and the filter 1 and the positioner members 72 are alignedso each positioner lies on top of one anchor member 30. When folded overthe filter so the positioner members 72 will fit within the storage tube15 or a delivery catheter 16, as illustrated in FIGS. 11 and 12, thepositioner members 72 can provide means to encircle the anchor members30 thereby retaining the anchor members. In the folded configurationwithin the storage tube 15 or delivery catheter 16, the positionermembers 72 lie approximately parallel to the longitudinal axis of thefilter 1 and filter positioning assembly 70.

In an embodiment, positioner members 72 in the folded configuration gripthe anchor members 30 sufficiently so that the pushing force required topush the filter 1 through the delivery catheter 16 by the push rod 60 istransferred from the positioner members 72 to the anchor members 30 andthen to the filter hub 2. As illustrated in FIG. 11, the positionermembers 72 may be sized to cover the anchor members 30 up to the pointwhere the locator members 20 overlap the anchor members 30 in the foldedconfiguration. Thus, for example, referring to filter 1 of FIG. 2, thepositioner members 72 of the assembly 70 are preferably defined by alength equal to L₂, which is the difference between the locator memberlength L₁ and the anchor member length L₃ in the folded configuration ofthe filter 1. The locator member length L₁ and anchor member length L₃can be any length suitable for use as an implantable device. Preferably,length L₁ can be from about 24 millimeters (about 0.95 inches) to about37 millimeters (about 1.5 inches) and length L₃ can be from about 36millimeters (about 1.4 inches) to about 52 millimeters (about 2 inches).

In an embodiment, the plurality of positioner members 72 are joined attheir proximal ends to the hub's periphery so that a pushing surface 73is formed on the hub 71, as shown in FIG. 7A. A central lumen 74 isprovided through the hub 71 and terminal portion 67 so that otherimplements (e.g., guidewire, borescope, saline, contrast agents and soon) can be transported from the proximal end of the catheter to thedistal end of the catheter.

In an embodiment, the hub 71 includes or is made of a radio-opaquematerial, which facilitates determining the location of the filter usingfluoroscopy. As used herein, a radio-opaque marker is any material thatis identifiable to machine or human readable radiographic equipmentwhile the material is inside a patient's body, such as, by way ofexample, but not by way of limitation, gold, platinum, barium sulfate,or tantalum.

The positioner members 72 preferably have a curved shape whenunconstrained, as illustrated in FIG. 7A, with a length and curvatureconfigured so that when the positioner members 72 are partially beyondthe end of the delivery catheter 16 their distal ends are in contactwith the walls of the blood vessel, as illustrated in FIG. 18.Accordingly, as the positioning assembly 70 exits the end of thedelivery catheter 16, the tips of the positioner members 72 bendradially outward and preferably away from the central lumen 74. Thepositioner members 72 are further configured so that they apply a springforce against the vessels walls when they contact the walls to positionthe end of the catheter near the blood vessel's centerline. Thepositioner members 72 are further configured so that when they are fullybeyond the end of the catheter, the members bend away from thelongitudinal axis (i.e., open) enough to release the plurality of anchormembers 30 of the filter 1. Thus, the size and shape of the positionermembers 72 will vary depending upon the internal diameter of the bloodvessel into which a filter is to be delivered, just as the sizes andorientations of filter locator and anchor members 20, 30 depend upon thesize of the intended blood vessel. Descriptions of various alternativepositioner member 72 shape and configuration embodiments are providedbelow with reference to FIGS. 8A-C and 9A-E.

When the ends of the positioner members 72 press against the vesselwall, the resulting spring force is transferred to the hub 71, andthereby provide a means to push the hub 71—and with it the end of thecatheter 16—toward the point of equal force among the various positionermembers 72, which will normally be at or near the centerline of theblood vessel. In order to hold the positioner members 72 in their flexedconfiguration and receive the applied force, the positioner members 72must be securely coupled to the hub 71. The positioner members 72 may beso coupled to the hub 71 by welding or brazing, or the hub 71 andpositioner members 72 may be machined from a single piece, such as, forexample, by removing the center portion down to the surface 73 followedby cutting out thin strips of metal (e.g., Nitinol or Elgiloy®) to formthe positioner members 72. As shown in FIGS. 7C and 7D, a unitarypositioner assembly 70B can be provided by cutting a generally tubularstock 70A to provide for the positioner members 72 and a central lumen.

An embodiment for assembling the filter positioning assembly 70 isillustrated in FIG. 7B. In this embodiment, the hub 71 is made up of asleeve 76 that fits over an internal plug 75. The internal plug 75 mayhave grooves 77 sized to accommodate an attachment portion 72D of thepositioner members 72 so that the sleeve fits close about the plug 75and positioner member 72. With the sleeve in place, the assembly may bewelded or brazed together into a rigid assembly.

The positioner members 72 may be formed in a variety of shapes. Threenonlimiting example embodiments are illustrated in FIGS. 8A-8C. In theembodiment illustrated in FIG. 8A, the positioner members 72 may be awire of relatively constant diameter, such as a circular, semicircularor elliptical cross section. While this embodiment features a constantcross section over its exposed length 72 a, which is the majority of themember's length, it may also include a thicker portion 72 d on itsproximal end for added strength that is shaped to fit into acorresponding groove 77 on the plug 75 described above. In anotherembodiment illustrated in FIG. 8B, the positioner members 72 may featurea varied geometry along their exposed length 72 a, which is the majorityof the member's length, such as narrow and cylindrical at the distalend, and wide and rectangular or in the form of an arch at the proximalend. This embodiment may also have a thicker portion 72 d on itsproximal end for added strength that is shaped to fit into acorresponding groove 77 on the plug 75 described above. This embodimentmay have design advantages because the tip portion, which pressesagainst the vessel wall, can be thin and thus more flexible so as toavoid damaging the endothelial layer, while the proximal end can spangreater width in order to better retain the anchor members until fulldeployment. In a third embodiment illustrated in FIG. 8C, the positionermembers 72 may be thin strips, such as of a rectangular cross sectionover their exposed length 72 a, which is the majority of the member'slength. Like the other embodiments illustrated in FIGS. 8A and 8B, thepositioner members 72 may have a thicker portion 72 d on their proximalends for added strength that is shaped to fit into a correspondinggroove 77 on the plug 75 described above.

The positioner members 72 may also have cross sectional featuresprovided to retain the anchor members 30 until release and provideadditional volume for accommodating the hooks 40 of filter 1. Forexample, FIG. 8C illustrates a step portion 72 b, which may be includedin any of the other embodiments of the positioner members 72. When thepositioner members 72 are coupled to the hub 71 to form the filterpositioning assembly 70, the step portion 72 b projects radially inwardtoward the centerline of the assembly. This creates a portion of theplurality of positioner members 72 having a narrower internal diameterfor retaining anchor members 30 at that point. Such a narrow diameter onthe interior of the positioner members 72 may tightly engage the anchormembers so that longitudinal force necessary to push the filter 1through the delivery catheter 16 can be transferred from the push rodassembly 60 to the filter anchor members 30 by the positioner members 72at this point. A thinner cross section portion 72 c may be providedadjacent to and on the proximal side of the narrower diameter formed bystep portion 72 b. This thinner cross section portion 72 c can provide alarger volume in the assembly to accommodate the hooks 40 on the ends ofthe anchor members 30 in the assembled, pre-delivery configuration.

In addition to their cross sectional configuration, the positionermembers 72 are characterized by their unconstrained shape over theirlength. In order to engage the blood vessel wall during delivery of thefilter 1, the positioner members 72 bend radially away from thelongitudinal axis of the filter positioning assembly 70. Thus, thepositioner members 72 have a curved shaped and are fixed to the hub 71so that their radiuses of curvature are outside the diameter of the hub71. The curved shape may be formed before or after the positionermembers 72 are coupled to the hub 71. When the positioner members 72 aremade from a shape memory alloy, such as Nitinol, the curvedconfiguration is set as the memory shape by annealing the member in theshape at high temperature, a step which may be completed either beforeor after the positioner members 72 are coupled to the hub 71. The shapememory alloy can further be defined as preferably having an austenitefinish (A_(f)) temperature below body temperature. Additionally, thepositioner member 72 can include an atraumatic tip such as, for example,a sphere, curved loop or a soft tip.

A number of positioner member 72 shape embodiments are possibleconsistent with the two functions performed by the structures. Forexample, FIG. 7A illustrates positioner members 72 with differentradiuses of curvature over their length and which do not bend through afull 180 degrees. This embodiment places the positioner members 72 underless strain when they are collapsed around a filter 1 in the deliveryconfiguration, illustrated in FIG. 11, and thus may be well suited forpositioner members 72 made from spring materials such as stainless steelor Elgiloy®.

Another exemplary embodiment is illustrated in FIG. 9A, in which thepositioner members 72 have a constant radius of curvature over theirexposed length. In the embodiment illustrated in FIG. 9A, the positionermembers 72 arch through a full semicircle (i.e., approximately 180degrees), though they may curve through more or less than 180 degrees.In this embodiment, the positioner members 72 curve outward as they exitthe delivery catheter 16, as illustrated in FIG. 9B, until they contactthe vessel wall. This embodiment of the positioner members 72 has anumber of advantages over the embodiment illustrated in FIG. 7A. Forone, the wide angle between the positioner members 72 adjacent to thehub 71 may facilitate releasing the anchor members 30 by providing moreclearance for the members to separate. For another, as the positionermembers 72 advance out of the delivery catheter 16 (such as by theclinician pulling the catheter 16 in the proximal direction whileholding the push rod 60 steady, as described more fully herein), thepositioner members 72 will tend to bow in the distal direction as theirtips are radially constrained by the blood vessel wall. This flexure mayprovide more space for releasing the anchor members 30 than may be thecase for positioner members 72 that do not further flex away from thelongitudinal axis, such as the embodiment illustrated in FIG. 7A.

Another example embodiment is illustrated in FIG. 9C, in which thepositioner members 72 have an approximately constant radius of curvatureover their entire length which is approximately equal to or longer thanthe circumference for that radius (i.e., L≈2*Π*radius). In thisembodiment, if the radius of curvature is set so that four times thatradius plus the width of the hub 71 is approximately equal to thediameter of the blood vessel, the positioner members 72 will apply anapproximately constant centering force against the vessel wall as thedelivery catheter 16 is retreated. Referring to FIG. 9E, as the deliverycatheter 16 is pulled back, the positioner members 72 will arch radiallyoutward until the ends contact the vessel wall, providing a centeringforce on the hub 71. Then, as the delivery catheter 16 is further pulledback, the distal end of the positioner members 72 will arch back awayfrom the vessel wall as illustrated in FIG. 9D so that the radialexpansion of the positioner members 72 does not increase as the deliverycatheter 16 is withdrawn. This curling over motion of the positionermembers 72 continues with further retraction of the delivery catheter16, as illustrated in FIG. 9C. Thus, in this embodiment, the maximumradial expansion of the positioner members 72 remains four times thatradius plus the width of the hub 71. It should be noted that while thedirection of curvature has been shown as counter-clockwise in FIGS.9A-9E, it is also preferred that the direction of curvature originatingfrom the catheter 16 is in a clockwise direction for FIGS. 9A-9E.Moreover, instead of a plurality of positioner members, a single helicalcoil can be used where the coil has an outside diameter at least asgreat as the blood vessel selected for implantation of a filter.

Since the embodiments illustrated in FIGS. 9A and 9C involve greaterstrain of the positioner members 72 to arrive at the pre-delivery,folded configuration illustrated in FIG. 11, these embodiments arepreferably made from a super-elastic shape memory alloy, such asNitinol. Using Nitinol, the shapes illustrated in FIGS. 9A and 9C can beset as the memory shape by annealing the positioner members 72 in theseshapes at high temperature. The shape memory alloy can further bedefined as preferably having an austenite finish (AD temperature belowbody temperature. After forming the members at high temperature, themembers can be cooled below the martensitic-to-austenitic transitiontemperature so they become pliable for folding over the filter 1 intothe configuration illustrated in FIG. 11. This alloy and method ofassembly helps ensure that the positioner members 72 are elasticallydeformed during packaging.

The filter positioning assembly 70 may include other features tofacilitate delivery of a filter into a blood vessel. For example, FIG.10 illustrates an embodiment that features an extension wire 79projecting from the hub 71 along the longitudinal axis of the assemblyfor a length L₃. Referring to FIG. 2, length L₃ is the length of theanchor members 30 from the filter hub 2. Thus, in this embodiment of thefilter positioning assembly 70, the extension wire 79 will reach up tothe base of the filter hub 2. Using a relatively stiff material for theextension wire 79, the member can transfer the pushing force directlyfrom the push rod 60 to the filter hub 2. This embodiment reduces thelongitudinal force of pushing the filter 1 through the delivery catheter16 that must be resisted by the anchor members 30. While the extensionwire 79 is shown for pushing the filter during deployment, analternative embodiment can be provided where the positioner members 72can be used to push on the filter hub 2 while the anchor members 30 arerestrained between a splined hub and the catheter. Details of thesplined hub and catheter to restrain the anchor members of the filterare shown and described in PCT International Application No.PCT/US06/17890, entitled “Embolus Blood Clot Filter and DeliverySystem,” filed on May 9, 2006, which is hereby incorporated by referencein its entirety.

From the foregoing, it can be seen that the various embodiments of thepositioner members 72 described herein and illustrated in the figuresprovide means for aligning a blood filter with a blood vessel centerlineand retaining anchor members of the filter until the alignment has beenaccomplished. The positioner members 72 also provide means for releasinganchor members 30 only after the blood filter has been aligned with theblood vessel centerline. Further, the push rod assembly provides meansfor pushing a blood filter through a delivery catheter and deploying thefilter in the blood vessel so the filter is aligned with the bloodvessel's center.

Preferably, during manufacturing, the filter positioning assembly 70 isfitted over the filter 1 and positioned within a storage tube 15. In theassembled configuration, illustrated in FIGS. 11 and 12, positionermembers 72 will be constrained by the walls of the storage tube 15 orcatheter 16 so that they lie approximately parallel to the longitudinalaxis, fitting tightly over the anchor members to present a narrow crosssection assembly that will fit within a delivery catheter. The combinedfilter positioning assembly 70 and filter 1 may be kept in a storagetube 15 which preferably has approximately the same internal diameter asthe delivery catheter and is configured to be coupled to the catheter bya clinician.

FIG. 12 illustrates an example of a suitable storage tube 15 containinga combined filter positioning assembly 70 and filter 1. The innerdiameter of the storage tube 15 resists radial expansion of the filter'slocator members 20 and the positioner members 72, keeping them lockedover the anchor members 30. In the embodiment illustrated in FIG. 12,the push rod terminal portion 67 is coupled to the hub 71 and includedwithin and/or extends from an end of the storage tube 15. Alternativeembodiments for connecting the terminal portion 67 to the hub 71 justbefore use are described herein with respect to FIGS. 14A-C. In anembodiment, the terminal portion 67 is coupled to the push rod assembly60 during storage, so the filter 1, storage tube 15 and push rodassembly 60 are packaged and stored as complete unit. In anotherembodiment, the terminal portion 67 includes a coupling mechanism thatallows the clinician to connect the terminal portion 67 to the rest ofthe push rod assembly 60 at the time of use. Any number of well-knownmechanisms for connecting rods together (e.g., threaded connections,bayonet fit, groove-and-detent fit, etc.) may be used for such aconnection.

Referring to FIGS. 12 and 30, the storage tube 15 for various bloodfilters may be provided with a suitable fitting (e.g., threaded, snap orluer fitting) at both ends for connection to other elements of adelivery system, such as described in more detail herein. In anembodiment, the storage tube 15 has a threaded fitting 15 b at one endto connect with a Touhy-Borst Adapter 10, such as is illustrated in FIG.29, and a snap fitting 15 a at the other end to connect with thedelivery catheter 16, as well as a taper section 15 c for insertion intoan elastomeric seal on the catheter. Alternatively, one end can beprovided with a snap-fitting and the other end can be provided with athreaded fitting. The storage tube 15 can be formed from any of a numberof suitable polymers and, preferably, polycarbonate.

To shorten the as-assembled filter positioning assembly 70 and filter 1combination so that it can be enclosed and sealed within a relativelyshort storage tube 15, a connectable fitting may be provided between thehub 71 and the push rod terminal portion 67. Such a connectable fittingmay be any known mechanical joining connection. Three nonlimitingexamples of known connections are illustrated in FIGS. 14A-C. Forexample, as illustrated in FIG. 14A, the terminal portion 67 may befitted with tabs 81 a that match corresponding grooves within a bore 81b in the hub 71 to provide a bayonet connection 81. In another example,illustrated in FIG. 14B, the end of the terminal portion 67 may bethreaded 82 a to match corresponding threads in a bore 82 b within thehub 71 to provide a threaded connection 82. In a third example,illustrated in FIG. 14C, spring tabs 83 a may be fixed to a nib end 83 bof the terminal portion 67 which will slip into a bore 83 c in the hub71 and latch into an internal ridge 83 d to provide a snap connection83. By using a connectable fitting, the filter positioning assembly 70and filter 1 may be stored in a relatively short sterilized and sealedstorage tube 15 that can be maintained in a conventional medicinalrefrigerator (e.g., in order to maintain Nitinol elements below themartensitic-to-austenitic transition temperature). Then, at the time ofuse, an end of the storage tube 15 may be opened and the filterpositioning assembly 70 connected to the terminal portion 67 of the pushrod assembly 60 by the clinician.

FIGS. 15-20 illustrate the structure and functioning of the variousembodiments delivering a filter into a blood vessel. In operation andstorage, the positioner members 72 remain tightly linked over the anchormembers 30, held in place by the walls of the storage tube 15 ordelivery catheter 16 until they are fully clear of the catheter. To helprestrain the filter anchor members 30 prior to deployment, the filterpositioning assembly 70 may include a spline 99 such as that illustratedin FIGS. 13A and 13B. The spline 99, which is preferably situated at ornear and more preferably formed in the positioning assembly hub 71,secures the filter anchor members 30 generally about the hub 71 andthereby prevents the filter hooks 40 from becoming entangled beforedeployment. The positioner members 72 may be integral with the spline 99and the spline may include a central lumen 98, as illustrated in FIG.13B.

In use, a clinician will typically position the delivery catheter 16 toa position in a blood vessel 6 where filter placement is desired. To aidthe clinician in this step, the delivery catheter 16 may have one ormore radio-opaque markers 160 near its distal end and at variouslengths, which can be imaged using fluoroscopy. With the catheter sopositioned, the filter positioning assembly 70 and filter 1 may beloaded into the proximal end of the delivery catheter 16 and advanced bypushing on the handle 61 of the push rod assembly 60 while holding thedelivery catheter 16 in a fixed position. When the filter 1 is near orjust beyond the end of the catheter 16, as illustrated in FIG. 15, thehub 2 is at the position where filter placement is desired. To helpconfirm the position of the filter 1, the hub 2 may include aradio-opaque marker that can be imaged by fluoroscopy equipment. At thispoint, the filter locator members 20 remain retained by the catheterwalls.

To deliver the filter, the clinician now extends the filter 1 andpositioner members 72 beyond the end of the delivery catheter 16. Thismay be done by either advancing the push rod assembly in the distaldirection while holding the catheter in a fixed position or, preferably,retracting the delivery catheter 16 in the proximal (withdrawal)direction while holding the push rod assembly 60 in a fixed position.The push rod assembly is advanced or the catheter 16 is retracted untilthe filter locator member tips clear the end of the catheter asillustrated in FIG. 16. Once free of the catheter, the locator membersdeploy so that their ends press against the vessel wall 6, therebycentering the filter hub 2 near the vessel centerline. At this point,the positioner members 72 retain the anchor members 30, preventing themfrom deploying.

As the push rod assembly is further advanced or the delivery catheter 16is further retracted, the positioner members 72 begin to be uncovered,which allows the tips of the positioner members 72 to flex radiallyoutward seeking their memory shape, as illustrated in FIG. 17. Once thepush rod assembly has been sufficiently advanced or the deliverycatheter 16 has been sufficiently retracted, the ends of the positionermembers 72 contact and press against the blood vessel wall 6 asillustrated in FIG. 18. The forces applied by the positioner members 72,being equal in all directions, center the distal end of the deliverycatheter 16 within the blood vessel 6. The combination of the centeringaction of the locator members 20 acting on the filter hub 2 and thepositioner members 72 acting on the catheter 16 and hook-ends of theanchor members 30 aligns the filter 1 approximately parallel with theblood vessel's centerline. At this point, the positioner members 72still retain the anchor members 30, preventing them from deploying untilthe aligning movements are completed. Then, when the delivery catheter16 is retracted a little further, the positioner members 72 are fullyreleased which by flexing away from the filter 1, release the anchormembers 30, as illustrated in FIG. 19. This allows the anchor members 30to spring radially outward toward their memory shape, pressing the hooks40 into the vessel wall 6, thereby anchoring the filter 1 in place.Finally, the clinician pulls the push rod assembly 60 in a proximaldirection while holding the delivery catheter 16 in a fixed position topull the positioner members 72 back into the catheter 16, as illustratedin FIG. 20. Once the positioner members 72 are securely within thedelivery catheter 16, the assembly can be removed from the patient'sbody.

An example of a suitable method for joining filter 1 with the filterpositioning assembly 70 and loading the combination in the storage tube15 is now described. The method comprises several steps. First, thecomponents are chilled below their martensitic-to-austenitic transitiontemperature so that the positioner members 72 and filter members, whichare preferably made from a shape memory alloy like Nitinol, areflexible. At this stage, the positioner members 72 are compressed, suchas by slipping a plastic tube over the members, and the filterpositioning assembly 70 are passed through the storage tube so they areaccessible on the other side, after which the plastic tube is removed.

Second, the filter is folded to its narrow profile configurationillustrated in FIG. 2. This may be accomplished by slipping a plastictube over the filter hub 2 and folding the locator members 20 and thenthe anchor members 30 toward the longitudinal axis while advancing thetube over the filter 1. The tube used for compression must only beadvanced far enough to collapse both the locator members and the anchormembers. The tube need not be advanced all the way to the hooks 40. Inthis stage, the compressed filter and surrounding plastic tube arepositioned so the anchor hooks rest against the hub 71 and are centeredamong the positioner members 72. The anchor members 30 should be alignedwith the positioner members 72.

Third, the storage tube 15 is moved slowly toward the filter and overthe positioner members 72. The walls of the storage tube force thepositioner members 72 to collapse toward the longitudinal access andclose over the anchor members 30. As the positioner members 72 collapseupon the anchor members, the plastic tube used to compress the filter isretracted so the tube does not become bound between positioner members72 and anchor members 30. This process continues until the positionermembers 72 are encompassed by the storage tube 15. At this stage, thepositioner members 72 will lie generally parallel to the longitudinalaxis and fully encircle the anchor members 30.

Finally, the storage tube 15 is advanced over the rest of the filterwith the plastic tube in place to hold the locator members in theircollapsed configuration. Once the entire filter 1 is within the storagetube 15, the plastic tube is withdrawn and the storage tube is sealed.To facilitate this method of assembly, the plastic tube may be clear andthin walled, with an external diameter just smaller than the insidediameter of the storage tube. This assembly process is performed priorto shipment to the user or medical practitioner. Other assembly methodsmay be used, and assembly may be facilitated by using other jigs orassembly tools to assemble the filter members within positioner members72 for loading into the storage tube 15.

To complete assembly, the storage tube 15 may be sealed on both ends toprevent contamination from entering, and the entire assembly of the pushrod assembly 60, filter 1 and storage tube 15 are sealed in sterilepackaging. To avoid kinking of the push rod assembly 60 or lateralforces on the storage tube 15, the entire assembly may be packed in alinear manner within a foam form and hard outer package, such ascardboard or plastic.

The various embodiments of the push rod assembly 60 will typically beused in combination with other filter delivery system components,particularly a catheter 16 that supports delivery of a filter into ablood vessel. A nonlimiting example embodiment of a filter deliverysystem suitable for use with the foregoing embodiments of the push rodassembly 60 follows with reference to FIGS. 21-30.

In overview, the blood filter delivery system 100 includes a storagetube 15 containing the filter 1, a catheter introducer 16 (“catheterintroducer” here refers to a particular embodiment of the deliverycatheter 16 so the same designation reference is used) and the push rodassembly 60 for pushing the filter 1 from the storage tube 15, throughthe catheter introducer 16 and then into the blood vessel, as well assupporting adapters illustrated in FIG. 21. The blood filter deliverysystem 100 for a blood filter device extends along a longitudinal axisA-A. Components of the system include an adapter 10, such as theTouhy-Borst Adapter shown in FIG. 29, a filter storage tube 15 (FIGS. 12and 30) that can be coupled to the Touhy-Borst Adapter 10 with a filter1 stored in the storage tube 15 along with one of the variousembodiments of the filter positioning assembly 70 that can be used todeploy the filter 1 in a blood vessel of a patient. Other componentsthat may be used with the system include a catheter introducer 16, shownin FIG. 22, and a catheter dilator 18, shown in FIG. 25. Each systemcomponent is described in further detail below.

Referring to FIGS. 22, 23, and 24, a catheter introducer 16 includes anelongated generally tubular member, referred to herein as the introducersheath 16 a coupled to a coupling port 16 b via an introducer body 16 c,which may be provided with a fluid valve 16 d. The elongated introducersheath member 16 a is coupled to the introducer body 16 c by suitablecoupling techniques, such as, but not limited to, threading, bonding,welding, swaging or adhesives. The introducer body 16 c can be providedwith an internal taper portion 16 f that allows for insertion of theexternal taper portion 15 c of the storage tube 15 (FIG. 30) and toallow for insertion of the filter hub 2 without interference bymisalignment of the storage tube 15 to the introducer sheath 16 a duringinsertion of the storage tube 15 into the introducer 16. Each of therespective taper portions 16 f and 15 c is preferably provided with ataper angle of about 10 degrees to about 45 degrees with respect to thelongitudinal axis A-A.

In various embodiments, the introducer sheath member 16 a may be formedfrom a range of biocompatible flexible materials, such as polyurethane,polyethylene, polyamide, polyether block amide (PEBA), nylon, andcombinations thereof, preferably from a combination of PEBA 70D withPEBA 55D proximate the tip 16 a 1. The introducer sheath member 16 a maybe connected to the introducer body 16 c by a bio-compatible adhesive,e.g., cyanoacrylates. In an embodiment, the distal tip 16 a 1 of theintroducer sheath member 16 a can be provided with a suitableradio-opaque marker 160, or include radio-opaque marker substanceswithin the material of the introducer tip 16 a 1. Preferably, a tantalumradio-opaque marker is formed on or near the tip 16 a 1 of theintroducer sheath 16 a.

In a preferred embodiment, the introducer sheath 16 a has an outsidediameter of less than about No. 10 French and an inside diameter of lessthan about No. 9 French and more preferably, an outside diameter ofabout No. 9 French or less and an inside diameter of about No. 7 Frenchor less, depending upon limits imposed by the diameter of the bloodfilter in the pre-deployed (i.e., folded) configuration.

The introducer body 16 c may be provided with a coupling port 16 b,which may include a fluid seal 16 e interposed between the port opening16 b 1 coupled to the introducer sheath member 16 a. The fluid seal 16 emay be any suitable seal, such as but not limited to, a membrane or aflexible arcuate sectioned seal disposed about a central opening.Preferably, the seal 16 e is an elastic membrane made of a suitablebiocompatible elastomer, e.g., silicone, with the arcuate sectioned sealdisposed about a generally central opening 16 b 1 for insertion of thedilator 18 or the filter storage tube 15. The introducer body 16 c maybe coupled to a fluid valve 16 d via a polymeric (e.g., PVC) tubing 16 gto allow for a suitable fluid (e.g., saline or a bio-active agentincluding drugs) to be introduced into the introducer sheath 16 a or todrain fluid from the introducer sheath 16 a. Preferably, the valve 16 dand introducer body 16 c are made of pol year bonate, polyethylene,polyurethane, polyamide or PEBA. The coupling port 16 b may be providedwith a circumferential edge that may be configured to act in a snap-lockarrangement with a complementary boss portion 18 f of the dilator body18 a to attach and retain the dilator body 18 a to the introducer body16 c. That is, the coupling port 16 b includes the introducer body 16 cthat has the port opening 16 b 1, which has a seal 16 e occluding theopening 16 b 1, and the introducer body 16 c has an edge 16 b 2 disposedabout the opening 16 b 1 so as to allow the introducer body 16 c to besecurable to a projection 15 a formed on one end of the storage tube 15via a sudden sharp engagement. The projection 15 a of the storage tube15 may include a curved surface disposed circumferentially about thelongitudinal axis A-A.

The use of complementary snap-fittings for the storage tube 15 andintroducer body 16 c along with the internal and external tapers 16 fand 15 c are believed to allow for precise coupling of these twocomponents without having to align the storage tube with the body 16 cand threading the two components together, which under somecircumstances could result in cross-threading or interference with thetip of the filter 1 into the introducer sheath 16 a.

Alternative embodiments of the introducer 16 may provide additionalcapabilities for delivering and inspecting a blood filter. In oneembodiment, an ultrasound imaging transducer is included in or near thedistal end 16 a 1 positioned to be capable of imaging the deploying anddeployed filter using ultrasound-imaging technology. An example of asuitable ultrasound transducer technology is disclosed in U.S. Pat. No.5,325,860, which is incorporated by reference herein in its entirety. Byincorporating an ultrasound imager within the introducer 16, a cliniciancan visually confirm the placement, deployment and emplacement of thefilter 1 before removing the introducer 16 while minimizing the use offluoroscopy. In an alternative embodiment, an ultrasound imagingtransducer may be passed through the introducer 16 after the push rodassembly 60 has been withdrawn following delivery of the filter 1. Thisembodiment allows the clinician to image the implanted filter beforeremoving the introducer 16 from the vicinity of the filter.

In another alternative embodiment, a fiber optic imager or borescope isincluded within the introducer sheath 16A to provide the clinician witha visual image of the deploying and deployed filter. A small lens on thedistal end of an optical fiber or bundle of optical fibers conveys animage to a small video camera on the proximal end. Illumination may beprovided to the point of inspection by another or the same opticalfibers. Such a fiber optic imager may be built into the wall of theintroducer sheath 16 a or be passed through the introducer sheath 16 aafter the push rod 60 has been withdrawn following delivery of thefilter. To aid in visualizing the implanted filter, saline solution maybe introduced in the introducer to displace blood in the volume beingimaged. Similar to an ultrasound imager, use of a fiber optic imagerwould permit a clinician to confirm the proper placement, deployment andemplacement of the filter before removing the introducer 16 whileminimizing the use of fluoroscopy.

The use of ultrasound or visual inspection of the deployed filter whilethe introducer 16 is in position near the filter may allow the clinicianto remove an improperly deployed or located filter and replace it withanother without requiring a separate procedure and before endothelialovergrowth of the filter hooks takes place. In this manner, if thefilter is improperly deployed and requires removal, the introducer 16 isalready adjacent to the filter and ready to be used in the removalprocedure.

A catheter dilator 18 is preferably used in conjunction with theintroducer 16. Referring to FIGS. 25-27, the dilator 18 includes adilator body 18 a coupled to a dilator tube 18 b. The dilator body 18 ais provided with a threaded fitting 18 f at the proximal end to connectto a suitable fluid valve, e.g., the Touhy-Borst Adapter 10 (FIG. 29) sothat fluids can be injected into the dilator fluid passage 18 g (FIG.28). A number of fluids may be injected during an operation, includingdye marker for enabling fluoroscopic imaging of the introducer 16 withinthe patient, saline to flush body fluids from and provide lubricationwithin the introducer 16 and, in some embodiments, cooled saline tomaintain temperatures of the push rod and/or the filter below theirmartensitic-to-austenitic transition temperature. The dilator body 18 ais coupled to a dilator tube 18 b that extends through and provides alongitudinal passage 18 g of approximately 26 inches (approximately 661mm) from the dilator body 18 a to the distal dilator end 18 c. At thedistal dilator end 18 c, the dilator tube 18 b may be provided with agenerally truncated conic tip defined by the outer surface of the distalend 18 c. The conic tip 18 c 1 can be defined by a conic outer surfacethat extends at a conic angle ⊖ of about 4 degrees with respect to thelongitudinal axis with an inside diameter ID of about 0.041 inches andan outside diameter OD of about 0.084 inches.

A plurality of fluid communicating ports 18 d may be provided throughthe wall of the dilator tube 18 b in a generally spiral configuration toallow for injection of contrasting dye. Each fluid communicating port 18d can be of a suitable configuration including, but not limited to,circular, square, or diamond. Preferably, as shown in FIG. 27, sixcircular communicating ports 18 d 1, 18 d 2, 18 d 3, 18 d 4, 18 d 5, and18 d 6 are provided with an opening diameter of about 0.037 inches. Eachport is preferably spaced equidistantly from the adjacent port over adistance d of about 0.16 inches along the longitudinal axis A-A andangularly disposed about the longitudinal axis A-A over an interval of60 degrees with respect to each adjacent port.

One or more radio-opaque marker bands 18 e may be coupled to the dilatorbody 18 a by a suitable technique, such as, but not limited to, forminga radio-opaque material integrally with the dilator tube 18 b ormounting a separate radio-opaque material onto or inside the dilatortube 18 b. Preferably, two radio-opaque markers 18 e are swaged onto thedilator tube 18 b near the distal end 18 c, with a first marker 18 e 1located approximately 1.1 inches (approximately 28 mm) from the tip 18 cand a second marker 18 e 2 located at approximately 1.1 inches(approximately 28 mm) from the first marker 18 e 1. In an embodiment,the ports 18 d 1-d 6 are arranged in a spiral configuration between tworadio-opaque marker bands.

The dilator tube 18 d may be formed from a variety of biocompatibleflexible materials, such as polyurethane, polyethylene, polyamide,polyether block amide (PEBA), nylon, and combinations thereof,preferably from a HDPE/LLDPE blend of polymer and 18-20% of bariumsulfate by weight, with the barium sulfate providing the radio-opaquefunctionality.

When assembled, the dilator tube 18 b slides inside the introducersheath 16 a such that the dilator tube tip 18 c 1 is close to theintroducer tip 16 a 1. The introducer 16 and catheter dilator 18 may bepackaged separately, such as in separate sterilized packages, so theycan be unsealed and assembled by the clinician at the time of theprocedure. Alternatively, the catheter dilator 18 may be inserted intothe introducer 16 at the manufacturer and sealed together in a sterilepackage, such that the clinician can unpack and use the two componentsas a unit.

Referring to FIG. 29, the Touhy-Borst Adapter 10 may be provided with atleast two passages. A first passage 10 a allows for movements of thepush rod assembly 60. A second passage 10 b allows for flow of salineinto the introducer 16 to increase lubricity between the push rodassembly 60 and the introducer 16 as the elongated push rod assembly 60is moved along longitudinal axis A-A through the second passage 10 b andthe passage of the introducer 16. The saline solution also may bechilled before introduction into the Touhy-Borst Adapter 10 in order tomaintain temperatures of the push rod and/or the filter below theirmartensitic-to-austenitic transition temperature.

Referring to FIG. 30, the storage tube 15 is provided with a suitablefitting (e.g., threaded, snap or luer fitting) at both ends. In anembodiment, the storage tube 15 has a threaded fitting 15 b at one endto connect with the Touhy-Borst Adapter 10 and a snap fitting 15 a atthe other end to connect with the introducer 16, as well as a tapersection 15 c for insertion into the preferably triple arcuate sectionedelastomeric seal 16 e.

The example filter delivery system may be used as follows for implantinga blood filter into a host. At the start, a suitable femoral venousvessel site in the host may be selected. Typically, this is the femoralvein on either the left or right side, depending upon the patient's sizeor anatomy, the clinician's preference and/or the location of a venousthrombosis. The site may be nicked with a blade and the vein puncturedwith a suitable entry needle, such as an 18-gauge needle, or trocar. Asuitable guide wire, such as a J-tipped guide wire, is inserted into theneedle and advanced into a distal vena cava or iliac vessel where afilter is to be delivered. Once the guide wire is in position, the entryneedle is removed from the patient and slipped off the proximal end ofthe guide wire. Then the proximal end of the guide wire is inserted intothe introducer distal tip 16 a 1 of the introducer 16. Saline or asuitable bio-compatible fluid is provided to the introducer valve 16 dto remove air in the introducer 16, and then introducer tip 16 a 1 (andpreferably both the introducer and dilator) is inserted into the patientand advanced along the guide wire until it reaches the desired positionin the vena cava or iliac vessel. Positioning of the introducer tip 16 a1 within the vein at the site for delivering the filter may be confirmedby fluoroscopy, aided by the radio-opaque markers on or within theintroducer 16. The dilator tube 18 b is then inserted through theintroducer body 16 c until the dilator hub 18 a is snap-fitted onto thecoupling port 16 b of the introducer 16. Contrasting agent or dye mayalso be provided to the ports 18 d of the dilator tube 18 b via thedilator body 18 a to provide for visual imaging of the introducer tip 16a 1 via suitable fluoroscopic imaging equipment. The guide wire and thedilator 18 can be removed once the user or physician has determined thatthe introducer tip 16 a 1 is at the desired location in the vein orvessel.

Saline infusion may be supplied to the Touhy-Borst Adapter 10. Thefilter 14, which is pre-stored in the storage tube 15, may be coupled tothe coupling port 16 b via the snap-fitting, and saline can be permittedto flow through the storage tube 15 to improve lubricity between variouscomponents of the delivery system 100. Alternatively, the saline may bechilled during portions of the procedure in order to help maintain thefilter 1 and push rod assembly 60 components below the super-elasticshape memory alloy martensitic-to-austenitic transition temperature sothat the positioning members, anchoring members and push wire portion 67remain flexible. Similarly, the saline may be warmed during portions ofthe procedure, such as just prior to releasing the filter into the vein,to help raise the filter 1 and filter positioning assembly 70 componentsabove the martensitic-to-austenitic transition temperature, causing thefilter to seek its annealed shape. The introducer 16, storage tube 15and elongated push rod assembly 60 are preferably held in a linearconfiguration to avoid kinking and minimize friction. The filter 1 isphysically advanced from the storage tube 15 through the introducer 16to a position near the distal tip 16 a 1 of the introducer 16. Theadvancement of the filter 1 can be accomplished by maintaining theintroducer 16 stationary while pushing on the handle 61 of the push rodassembly 60 in the distal direction. The filter 1 is maintained insidethe introducer 16, i.e., undeployed at this point. Markings on the pushrod assembly 60 may permit the clinician to know the position of thefilter 1 with respect to the end of the introducer 16. Additionally,fluoroscopy may be used to track the position of the filter 1 within theintroducer 16 and with respect to the patient. When the filter hub 2approaches the distal end of the introducer 16, as is shown in FIG. 15,the filter is ready to be deployed. At this point, the filter deliverysteps described above with reference to FIGS. 15-20 will be implemented.

While the present invention has been disclosed with reference to certainpreferred embodiments, numerous modifications, alterations, and changesto the described embodiments are possible without departing from thesphere and scope of the present invention, which is described, by way ofexample, in the appended numbered paragraphs below. Accordingly, it isintended that the present invention not be limited to the describedembodiments, but that it has the full scope defined by the language ofthe following claims, and equivalents thereof.

What is claimed is:
 1. A blood filter delivery apparatus for deliveringa blood filter into a blood vessel having a vessel wall, the bloodfilter including a plurality of filter appendages, the apparatuscomprising: a) a catheter having a free end portion with a catheteropening and a catheter wall with an inner surface surrounding a catheterlumen, wherein the catheter opening communicates with the catheterlumen; b) a filter positioning assembly situated with the filter withinthe catheter lumen to define a stored position, the filter positioningassembly including a plurality of positioner members coupled to theassembly, each of the plurality of positioner members having an end thatis connected to one of said filter appendages within the catheter lumen,wherein the ends of the positioner members and the filter appendages areconnected within the catheter lumen in said stored position; c) whereinthe filter is positioned closer to the catheter opening than thepositioning assembly; d) a pusher that engages the positioning assemblyand filter inside the lumen, wherein the positioning assembly and filterare movable between said stored position within the catheter lumen and apreliminary dispensed position wherein the positioning members engagethe vessel wall while at least a portion of some of the filterappendages remain inside the catheter lumen; and e) wherein the bloodfilter includes a head, wherein said plurality of filter appendages areconnected to said head and wherein in said stored position, said head iscloser to the catheter opening than said filter appendages.
 2. A bloodfilter delivery apparatus for delivering a blood filter into a bloodvessel having a vessel wall, the blood filter including a plurality ofappendages, the apparatus comprising: a) a catheter having a free endportion with an opening and a catheter wall with an inner surfacesurrounding a catheter lumen; b) a filter positioning assembly situatedwithin the catheter lumen to define a stored position, the filter havingmultiple filter legs, the filter positioning assembly including aplurality of positioner members coupled to the assembly, each of theplurality of positioner members having an end that is connected to oneof the plurality of appendages within the catheter lumen, wherein theends of the said positioner members and the said appendages areconnected within the catheter lumen; c) wherein the filter is positionedin between the catheter opening and the positioning assembly; and d) apusher that engages the positioning assembly and filter inside the lumenin said stored position, wherein the positioning assembly and filter aremovable between said stored position within the catheter lumen and apreliminary dispensed position wherein some of the filter legs engagethe vessel wall while at least a portion of some of the filter legsremain inside the catheter lumen.
 3. The blood filter delivery apparatusof claim 2, further comprising a hub coupled to the said plurality ofpositioner members, the said plurality of positioner members being inbetween the hub and the catheter open end in the stored position.
 4. Theblood filter delivery apparatus of claim 3, wherein the hub includes atleast one spline configured to retain the plurality of positionermembers.
 5. The blood filter delivery apparatus of claim 3, wherein thehub, spline and plurality of positioner members are formed integrally.6. The blood filter delivery apparatus of claim 3, wherein the hub has acentral hub lumen.
 7. The blood filter delivery apparatus of claim 2,wherein in the preliminary dispensed position the plurality ofpositioner members are configured to extend radially to define acatheter centerline as the filter positioning assembly and a portion ofthe filter exits the open end of the catheter.
 8. The blood filterdelivery apparatus of claim 7, wherein the said plurality of positionermembers locate the end of the catheter substantially along thecenterline so as to further locate the end of the catheter centrallywithin the blood vessel.
 9. The blood filter delivery apparatus of claim7, wherein in an installed position the plurality of appendages areunconstrained by the catheter after an end of the catheter is positionedsubstantially along the centerline.
 10. The blood filter deliveryapparatus of claim 2, wherein the plurality of positioner members are ofa Nitinol material.
 11. The blood filter delivery apparatus of claim 2,wherein the filter positioning assembly has a longitudinal axis, andfurther comprises an extension wire oriented along the longitudinal axisand configured to contact a hub of the filter when the plurality ofappendages are retained by the plurality of positioner members.
 12. Theblood filter delivery apparatus of claim 2, wherein the pusher includesan elongated push rod coupled to the filter positioning assembly. 13.The blood filter delivery apparatus of claim 2, wherein the plurality ofpositioner members each have a constant cross section over a majority ofits length.
 14. The blood filter delivery apparatus of claim 2, whereinthe plurality of positioner members each have a proximal end and adistal end to define a length therebetween, at least one positionermember having a variable cross section over a majority of the length.15. The blood filter delivery apparatus of claim 14, wherein the atleast one positioner member has a cross section at the proximal endgreater than the cross section at the distal end.
 16. The blood filterdelivery apparatus of claim 14, wherein the at least one positionermember has a cross section at the proximal end less than the crosssection at the distal end.
 17. A blood filter delivery apparatus fordelivering a blood filter into a blood vessel having a vessel wall, theblood filter including a plurality of appendages, the apparatuscomprising: a) a catheter having a free end portion with an opening anda catheter wall with an inner surface surrounding a catheter lumen; b) afilter positioning assembly situated within the catheter lumen to definea stored position, the filter having multiple filter legs, the filterpositioning assembly including a plurality of positioner members coupledto the assembly; c) wherein in said stored position each positionermember of said plurality of positioner members has an end that isconnected to a said filter leg within the catheter lumen and the ends ofsaid positioner members and said plurality of appendages are connectedwithin the catheter lumen; d) wherein the filter is positioned inbetween the catheter opening and the positioning assembly; e) a pusherthat engages the positioning assembly and filter inside the lumen insaid stored position; and f) wherein the positioning assembly and filterare movable between said stored position within the catheter lumen and apreliminary dispensed position wherein some of the filter legs engagethe vessel wall while at least a portion of some of the filter legsremain inside the catheter lumen.